1. Field of the Invention
The present invention relates to devices for optical storage and retrieval of information and, more particularly, to optical disks which provide greater density for storage and retrieval of information, to correspondingly configured optical readers and to optical readers configured to increase the reliability and rate of transfer of information to be stored or retrieved.
2. Related Art
Storing data on media that is optically read and/or written to is known. As illustrated in FIG. 1, a typical optical disk 10 comprises a radially extending body or substrate 12 having discontinuities such as lands 14 located on a side 16 thereof. The lands 14 are arranged together to form a track 18 which includes windings 20 which spiral about the side 16 of the substrate 12. The lands 14 have outer edges 22 which may each be read by an optical head (not shown) as an instruction, e.g., to go high.
Each winding 20 of the track 18 may be separated by a distance (D) of 740 nanometers and each land may dimension 400 nanometers in length (L) by 320 nanometers in width (W). A thickness (T) of the land may be approximately 120 nanometers.
Accordingly, the amount of data which may be stored on an optical disk 10 is limited by the radial dimension of the disk. With increasing demands for data storage capability, a need exists for increasing the storage capacity of the optical disk.